If you want to reduce body lean caused by wind gusts, I do not believe that a bigger front swaybar would be the best answer to that. The increased stiffness of the sway bar would upset the roll-couple distributation (front-to-rear roll balance) with minimal improvement in your original goal of reducing wind-induced sway.
If one could source suspension dampners that were valved for increased rebound dampning, this would help. In addition, any lowering of the front and rear ride height would help, but most likely at the expense of ride quality. Increasing the front and rear track width, along with a slight increase in spring rates, would also help.
The real problem here is the Smart was designed to be tall and narrow. The height helps create its great interior room and the narrow width contributes to nimbleness.
So what makes it great in some ways, hurts in others.
This is the story of my life as well!